Step 3.5 Flash
StepFun • LLM
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....
Specifications
Context Window
262K tokens
Input Price/1M
—
Output Price/1M
—
Parameters
—
Speed
202 tok/s
Latency (TTFT)
885ms
Max Output
66K tokens
Benchmarks
Step 3.5 Flash results on the main AI model evaluation benchmarks. Higher scores indicate better performance.
Agentic
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Terminal-Bench Hard | 33.0 | 100.0 | — |
Coding
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| SciCode | 40.0 | 100.0 | — |
| AA Coding Index | 31.6 | 100.0 | Artificial Analysis official API |
Long Context
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AA-LCR | 54.0 | 100.0 | — |
overall
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AA Intelligence Index | 37.8 | 100.0 | Artificial Analysis official API |
Reasoning
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| GPQA Diamond | 83.1 | 100.0 | Artificial Analysis official API |
| IFBench | 67.0 | 100.0 | — |
| HLE | 23.0 | 100.0 | — |
Tool Use
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Tau²-Bench | 94.0 | 100.0 | — |
Information
- Release date
- April 02, 2026
- Tool Calling
- ✅ Supported
- Vision
- ❌ Not supported
- Audio
- ❌ Not supported
Full Analysis: Step 3.5 Flash
What is Step 3.5 Flash?
Step 3.5 Flash is an AI model developed by StepFun, classified as a large language model (LLM). It focuses on text processing and natural language generation. As an open source model, it is available for download, customization, and on-premises deployment. With a context window of 262K tokens, it is suitable for processing long documents such as contracts, books, and complete codebases.
Pricing & Costs in 2026
Step 3.5 Flash does not have public per-token pricing available at this time. Some models offer access via enterprise plans or research programs. Check StepFun's official website for up-to-date availability and pricing.
Benchmarks & Performance
Step 3.5 Flash was evaluated on 9 different benchmarks, covering categories like Agentic, Coding, Long Context, overall, Reasoning, Tool Use. Results show exceptional performance across available evaluations.
It's important to note that benchmarks measure specific aspects and don't capture the full user experience. Factors like instruction adherence, behavior in long conversations, and real-world task quality vary significantly between models and aren't always reflected in standard scores.
Recommended Use Cases
Step 3.5 Flash is suitable for a wide range of AI applications: long document analysis (contracts, legal proceedings, codebases), automation with tool calling (API integration, databases, external systems), complex reasoning, math problem solving, and logical analysis, text generation, summarization, translation, and general assistance.
Comparison with Alternatives
In the 2026 AI model ecosystem, Step 3.5 Flash competes directly with similarly capable models. StepFun competes in this segment against OpenAI, Anthropic, Google, and Meta. The choice between models depends on the specific use case, budget, latency requirements, and need for features like multimodality and tool calling.
For a detailed side-by-side comparison, use our comparison tool or check the overall model ranking.
Frequently Asked Questions
What is Step 3.5 Flash?
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....
How much does Step 3.5 Flash cost?
Step 3.5 Flash does not have public per-token pricing available at this time. Check StepFun's official website for up-to-date information.
How does Step 3.5 Flash compare with other models?
In available benchmarks, Step 3.5 Flash scored: Terminal-Bench Hard: 33/100, SciCode: 40/100, AA Coding Index: 31.6/100. See the full table above for a detailed comparison.
Is Step 3.5 Flash open source?
Yes, Step 3.5 Flash is an open source model. You can deploy it on-premises, customize it via fine-tuning, and maintain full control over your data. Check the official repository for the specific license.
What is Step 3.5 Flash best for?
Step 3.5 Flash excels at complex reasoning and problem solving. With its large context window, it handles long documents, codebases, and extended conversations. It supports tool calling for API integrations and automation.
Last updated: May 22, 2026 • View methodology →